In recent years, there has been an increasing use of compact, pocket-size electronic personal organizers that store personal scheduling information such as appointments, tasks, phone numbers, flight schedules, alarms, birthdays, and anniversaries. Some of the more common electronic organizers are akin to hand-held calculators. They have a full input keyboard with both numeric keys and alphabet keys, as well as special function keys. The organizers also have a liquid crystal display (LCD) which often displays full sentences and rudimentary graphics.
Pocket-size personal organizers prove most useful to busy individuals who are frequently traveling or always on the move from one meeting to the next appointment. Unfortunately, due to their hectic schedules, these individuals are the people most likely to forget their personal organizers during the frantic rush to gather documents, files, laptops, cellular phones, and travel tickets before heading off to the airport or train depot. It would be desirable to reduce the number of electronic devices that these individuals need to remember for each outing.
Electronic watches have evolved to the point that they can function as personal organizers. Like the pocket-size devices described above, such watches can be programmed with certain key appointments, tasks, phone numbers, flight schedules, alarms, birthdays, and anniversaries. Since watches are part of everyday fashion attire, they are more convenient to carry and less likely to be forgotten by busy people. However, it is much more difficult to enter data into a watch than it is to enter the same data into a pocket-size personal organizer. This difficulty is due in large part to the limited number of input buttons and display characters available on reasonably-sized watches. Most watches are limited to having only three or four input buttons. A wearer programs a watch by depressing one or more buttons several times to cycle through various menu options. Once an option is selected, the user depresses another button or buttons to input the desired information. These input techniques are inconvenient and difficult to remember. Such techniques are particularly inconvenient when a wearer wishes to enter an entire month's schedule. Although watches have been made with larger numbers of input keys, such watches are usually much too large for comfort, and tend to be particularly unattractive.
Apart from personal organizers, it is common for many people to maintain appointment calendars and task lists on their personal computers. One example time management software is Microsoft's.RTM. Schedule+.TM. for Windows.TM. which maintains daily appointment schedules, to-do lists, personal notes, and calendar planning. This information is often a duplicate of that maintained on the portable personal organizer.
Timex Corporation of Middlebury, Conn., has recently introduced the Timex.RTM. Data Link.TM. watch. This watch utilizes new technology for transferring information from a personal computer to a watch. The face of the watch has an optical sensor which is connected to a digital serial receiver, better known as a UART (universal asynchronous receiver/transmitter). The watch expects to receive a serial bit transmission in the form of light pulses at a fixed bit rate. A pulse represents a binary `0` bit, and the absence of a pulse represents a binary `1` bit.
The CRT (cathode ray tube) or other scanned-pixel display of a personal or desktop computer is normally used to provide light pulses to the watch. Although it appears to a human viewer that all pixels of a CRT are illuminated simultaneously, the pixels are actually illuminated individually, one at a time, by an electron beam which sequentially scans each row or raster line of pixels beginning with the top raster line and ending with the bottom raster line. It is this characteristic of a CRT and of other frame-scanning display devices which is utilized to transmit serial data to the Data Link.TM. watch.
To transfer data to the watch, the watch is held near and facing the CRT. The computer is programmed to display a sequence of display frames in which selected spaced raster lines represent individual bits of data. Lines are illuminated or not illuminated, depending on whether they represent binary `0` bits or binary `1` bits. Each line appears as a continuous pulse of a finite duration to the receiving watch. The watch recognizes an illuminated line as a binary `0` bit. It recognizes a non-illuminated line as a binary `1` bit. Generally, ten bits are transmitted in a single CRT display frame: eight data bits, a start bit, and a stop bit. A display frame is generally created by sequentially illuminating or refreshing the raster lines of the display device.
FIG. 1 shows a specific pattern of selected and spaced raster lines used to transmit data from a CRT to a watch. Assuming that each CRT display frame transmits a single 8-bit byte with start and stop bits, ten raster lines 30(1)-30(10) (out of a much larger total number of available raster lines) are selected for transmitting data. These raster lines will be referred to herein as "data transmission raster lines," as opposed to other, intervening raster lines which will be referred to as "unused raster lines." Solid lines in FIG. 1 represent data transmission raster lines which are illuminated. Dashed raster lines in FIG. 1 represent data transmission raster lines which are not illuminated. Each data transmission raster line position conveys one data bit of information. Bits having a first binary value, such as a value `0`, are represented by illuminated data transmission lines (e.g., lines 30(1), 30(2), 30(4), and 30(7)-30(9)) and bits having a second binary value, such as a value `1`, are represented by non-illuminated data transmission lines (as illustrated pictorially by the dashed lines 30(3), 30(5), 30(6), and 30(10)). The data transmission raster lines are spaced at a selected intervals, with intervening unused or non-selected raster lines, to produce a desired temporal spacing appropriate for the data receiving electronics of the watch.
For each programming instruction or data to be transmitted to the watch, the software resident in a personal computer causes the associated CRT to selectively illuminate the appropriate data transmission raster lines representing `0` bits by scanning the associated pixels. The selected data transmission lines that represent `1` bits are left non-illuminated. The middle eight lines 30(2)-30(9) represent one byte of programming information being optically transmitted to the watch 12. Top line 30(1) represents a start bit and bottom line 30(10) represents a stop bit that are used for timing and error detection. Because of the scanning nature of the cathode ray of the CRT, these patterns produce a serial light emission from the CRT which is representative of a serial bit stream. Each display frame represents one byte. A new line grouping is presented for each sequential display frame so that each such display frame represents a different data byte. Two or more bytes could optionally be transmitted in each display frame.
One disadvantage of the system described above is that the Data Link.TM. watch expects to receive data at a very specific bit rate of 2048 bits per second. This is accomplished by correctly establishing the spacing of data transmission raster lines used on the display device for data transmission. The spacing can be controlled by varying the number of unused raster lines between the data transmission raster lines. The correct spacing, however, depends on the rate at which the display device scans or updates its pixels and raster lines. Not all display devices use the same scanning rate. Accordingly, manual or automatic calibration routines are needed to determine or measure the scan rate of the display device. Unfortunately, such routines are sometimes difficult to implement. This is especially the case when operating under multi-tasking operating systems such as Microsoft's Windows.RTM. '95 operating system. An operating system such as Windows.RTM. '95 discourages close interaction between application programs and computer hardware, making direct measurement of a CRT's scan frequency very difficult.